The present invention relates to an encoding device, a decoding device, an encoding method, a decoding method, a program, a program recording medium, and a data recording medium. More specifically, the invention relates to an encoding device, a decoding device, an encoding method, a decoding method, a program, a program recording medium, and a data recording medium which use Reed-Solomon codes.
According to Japanese patent No. 3272307, Reed-Solomon codes or BCH codes used for a communication device or the like which needs high reliability are used as product codes, and decoding is iterated to enable error correction by a higher coding gain than that of a system standardized by ITU-T. G. 709. For example, according to “Enabling Next Generation Optical Networks with Forward Error Correction”, by S. Keeton,, S. Sridharan, and M. Jarchi, pp. 54 of National Fiber Optic Engineers Conference 2001, a method of executing error correction by using BCH codes as product codes, and iterative decoding has been presented.
According to the above-described method, in an area of a relatively high error rate in which a bit error rate (BER) is about 10−5, error correction of a large coding gain can be executed. However, in recent optical communications or the like, because of a high communication data rate, preferably, BER after addition of error correction codes is limited to about 10−15 or higher. In such a case, the above-described method may be adversely affected by an error floor of an escape pattern to disable acquisition of a sufficient coding gain. The method which needs a large number of iterations is not preferable from the standpoint of a circuit size and power consumption.